It is personally impossible for me to OC my cpu as i know nothing and have read many tutorials but to no avail. I am planning to buy a GTX 460 1 GB and a PSU, and buying a new CPU and Ram is too much on my budget. So, can someone please tell me how to reduce bottlenecking without OC'ing my CPU.

Technically downclocking your GPU will reduce the bottleneck... But on a more serious note, you can't really expect to squeeze more performance out of your system without spending extra money or overclocking. I would say though, at your screen resolution, you should be able to max every game (save a few optimized for quad-core games).